The present invention relates to a process for reprocessing plastic by-products.
In the preparation of plastics, by-products are necessarily formed in the polymerization step. In the preparation of polypropylene, for example, atactic polypropylene is formed in the intermediate step. The amount of the atactic polypropylene formed is 5 to 10% by weight based on the total weight of polypropylene. This by-product, that is, atactic polypropylene is nowadays chipped and used as a fuel, or burned in a special furnace, or incorporated into asphalt for road paving. However, the amount of the by-product used is very small as compared with the amount thereof formed. Thus, there is a limited demand for it. In some cases, atactic polypropylene contains titanium tetrachloride as a catalyst according to the polymerization procedure. In such cases, hydrogen chloride is generated on heating or burning and it may cause the second environmental pollution. Also, it causes troubles in environmental protection to discard the by-product simply. Therefore, the by-product must be tipped carefully for land-fill. Further, it is difficult owing to its strong tackiness to crush the by-product at room temperature. At any rate, one is nowadays at a loss how to treat the by-product.
An object of the present invention is to provide a process for reprocessing plastic by-products according to which a reprocessed material utilizable effectively as a bulking filler for the virgin plastic or for the other uses can be obtained.